Machankura - Send Bitcoin With Old Feature Phones Without an Internet Connection

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@Machankura8333 is a project that lets users send and receive #Bitcoin with old-school feature phones without an internet connection. How does Machankura work and how it could boost Bitcoin adoption and also potentially be the best way to orangepill your grandma? Thread 🧵 👇

1/15 Machankura (South African slang for "money") is targeting people in Africa without a smartphone connected to the internet. For this reason, they can't send or receive BTC on their phones. It's estimated that this applies to around 70% of the people on the continent.

2/15 Mobile money, however, has been a popular way to exchange value for over a decade. It involves a communications protocol called USSD (Unstructured Supplementary Service Data), which is similar to the more widely known texting protocol called Short Message Service (SMS).

3/15 USSD is a bit like a dumb chatbot or a "choose-your-own-adventure" game that gives user a decision tree. You may have interacted with USSD if you've ever topped up a prepaid mobile plan by dialing a specific number to choose your preferred plan.

4/15 To use USSD, the phone doesn't need to be connected to the internet. Machankura links a user's phone number to a Lightning address. To send BTC for the first time, a user dials a country code + 8333#. This brings up a registration menu that requests a 5-digit PIN code.

5/15 Machankura uses 8333 as a domain name because 8333 is the main Bitcoin port nodes use in order to connect. After registering, a menu opens up where users can send/receive BTC or view their transaction history by pressing a relevant button on their feature phone.

6/15 Under the hood, Machankura runs a web server where all the SMS messages are sent, plus Bitcoin and Lightning nodes. The web server communicates with Machankura's Lightning node that is keeping track of the users' BTC payments.

7/15 Machankura users have personalized Lightning addresses. By default, they combine a user's phone number and Machankura's “@8333.mobi” domain, e.g. 123456@8333.mobi Users can also replace their phone numbers with aliases, e.g. satoshi@8333.mobi

8/15 These personalized addresses are easy to type out with feature phones using multi-press text entry (where each digit represents multiple letters/numbers). Machankura is a custodial wallet and takes a 1% transaction fee from the sender.

9/15 You can't buy BTC with Machankura, but you can buy an @Azteco_ voucher (easily accessible e.g. in South Africa) and top up your wallet with it. For cashing out, you can use e.g. @bitrefill with a direct API integration with Machankura to buy airtime, restaurant vouchers...

10/15 The wallet shows the balance both in sats and local currency. This helps adoption because prices are not (at least yet) listed in sats! It's good to note that Machankura can only send to LNURL addresses (therefore you can't send e.g. to the popular Muun wallet).

11/15 The downside of Machankura is that it's a very centralized solution in the Bitcoin Lightning economy. The founder @440UrPp said that he started it as a hobby project running it all by himself with 2 Raspberry Pi single-board computers!

12/15 However, a centralized solution is often needed to bootstrap adoption. With Machankura, Bitcoin can become the most accessible asset throughout Africa. Machankura is currently available in Ghana, Kenya, Malawi, Namibia, Nigeria, South Africa, Uganda and Zambia.

13/15 Africa, with its large and young population will be a main driver to widespread Bitcoin adoption. But it would also be interesting to see a similar project on other continents where using mobile data is still lagging behind (e.g. Latin America or South East Asia).

14/15 The cheapest smartphones don't have much storage, so after installing some essential apps, users often don't have enough storage for a BTC wallet. Also, data bundles often give users free FB, IG, WA etc., so they might not even have data to receive BTC LN txs on the go

15/15 A non-custodial version of Machankura could also be possible. This solution would use SIM cards as private keys to sign transactions. These keys would then be connected to e.g. Lightning channels with a multisig support.

Finally, a presentation by @440UrPp from November 2022 at the @AdoptingBTC conference in El Salvador: youtube.com/watch?v=yknBN08hWOY